Nonaqueous electrolyte secondary batteries are categorized into cylindrical batteries, prismatic batteries and pouch batteries according to the shape of battery cases. Electrode assemblies accommodated into battery cases are divided into the wound type and the stack type. A wound electrode assembly is fabricated by winding a positive electrode plate and a negative electrode plate together via a separator and fixing the end of the coil to the body of the electrode assembly with a fixing tape. The electrode assembly is then accommodated into a battery case, and an electrolytic solution is poured. Thereafter, the open end of the battery case is sealed to form a nonaqueous electrolyte secondary battery. In nonaqueous electrolyte secondary batteries, the time required for the penetration of an electrolytic solution varies depending on the configuration of an electrode assembly. Thus, the ease for an electrode assembly to be impregnated with an electrolytic solution is considered as a factor that has a significant influence on the productivity of nonaqueous electrolyte secondary batteries.
In recent years, the increasing demand for a higher capacity of nonaqueous electrolyte secondary batteries has resulted in an increase in the density in which components such as active materials and a separator are loaded into electrode assemblies. This trend has made it difficult for the electrode assembly to be impregnated with an electrolytic solution speedily. Further, the swelling of electrode plates during charging causes a separator to be pressed against the electrode plates, sometimes resulting in a voltage failure in which the voltage is decreased after the charging.
Patent Literature 1 discloses a method for manufacturing batteries in which the inside of a battery case accommodating an electrode assembly is pressurized to a prescribed pressure before the pouring of an electrolytic solution and is depressurized to atmospheric pressure. According to the disclosure, the pressurization and depressurization before the pouring of an electrolytic solution allow the electrode assembly to be impregnated with the electrolytic solution speedily.
Patent Literature 2 discloses a wound secondary battery in which the end of an electrode assembly is fixed to the body of the coil with a self-adhesive tape having a pressure-sensitive adhesive only on portions of a substrate. This self-adhesive tape is applied to the electrode assembly so that the adhesive-free portion will cover the end of the coil. According to the disclosure, the electrode assembly is impregnated with an electrolytic solution that has entered through the end of the coil.
Patent Literature 3 discloses a nonaqueous electrolyte battery in which an electrode assembly is fastened with a fixing tape which has dots of a pressure-sensitive adhesive scattered on a substrate of the tape. In this nonaqueous electrolyte battery, the regions of the fixing tape that are free from the pressure-sensitive adhesive are impregnated with an electrolytic solution quickly and the fixing tape comes off from the electrode assembly with the result that the electrode assembly is relaxed. According to the disclosure, the occurrence of a voltage failure is prevented by virtue of this action even in the case where the electrode assembly is highly loaded.